Transfection or transformation is referred to the technology for transporting the genetic materials into cells or organisms. For instance, an electric field is performed on the plasmid DNA, and the plasmid DNA then is transported into cells to express its biological functions or to be translated as specific proteins. Alternatively, liposome with positive charge is mixed with negative charge DNA to form complex, and DNA is delivered to cytoplasm by the fusion of the complex with cell membrane or endocytosis.
U.S. Pat. No. 6,846,809 discloses a DNA vector for DNA delivery, wherein nucleic acid and polycation are mixed to form a liquid transfection composition, which directly contacts with cancer cells or tissues having cancer cells, so that nucleic acid is delivered to cancer cells to inhibit their growth. However, since no external electric field or magnetic field is performed on the liquid transfection composition, the transfection efficiency is not high.
In recent years, the magnetic transfection technology is developed, which integrates the genetic materials such as DNA, small interfering RNA (siRNA) and so on with magnetic nanoparticles to transport the genetic materials using a magnetic field. For instance, US Patent Publication No. 2008/0075701 discloses a composition for magnetofection, which envelopes the magnetic nanoparticles (MNPs) and the genetic materials inside the hydrophilic vector (liposome) to form the spherical vehicle. At first, the MNPs are coated with surfactant (organic acid), and the excess surfactant is removed with ultrasonication. The MNPs then are enveloped inside the liposome, but surfactant is not enveloped thereinside. Subsequently, the genetic materials are added to the fluid containing liposome-enveloped MNPs, and the genetic materials pass into the liposome via the lipid bilayer structure to form the end product, the spherical vehicle. However, the processing steps of the MNPs in US 2008/0075701 are too complicated, and the genetic materials need to pass through the lipid bilayer structure to be enveloped with the liposome. Thus, it will reduce the probability that the nanoparticles and magnetic materials are enveloped inside the liposome at the same time.
The MNP based on iron oxide nanoparticles can be degraded in physiological conditions over a time period of a month suspiciously corresponding to ferritin synthesis (Briley-Saebo et al., 2004). Since the internalized iron oxide nanoparticles are biotransformed, thus, there would be no safety concern using MNPs as a drug delivery system.